Various equipment has been developed to increase the safety of persons using mobile storage systems. Such equipment is desirable to prevent a carriage from starting or continuing to move when a person is in an aisle next to the moving carriage. Movable carriage control is especially important in electrically powered systems, because a carriage can then be operated from a remote location and because of the large drive forces produced by the carriage motors.
Prior safety designs for preventing start-up of a stationary electrically powered carriage and for stopping a moving carriage in response to a potential safety problem may be seen in U.S. patent application Ser. Nos. 839,966 now U.S. Pat. No. 4,693,184 issued 9/15/87, and 822,846. In those designs, various types of switches are employed to control the electric motors that drive the movable carriages. If a person actuates a switch, associated control circuitry operates to deenergize the motors and stop the carriage.
Although the prior designs have been successful, certain additional features are considered desirable for maximizing personnel safety. Thus, a need exists for improved safety devices in combination with mobile storage systems.